The present invention relates to the composition of, and processes for making, products for infant formulas and for nutritional products suitable for both infants and adults, and particularly for clinical nutrition. These products may be administered orally or by enteral feeding tubes. These products are enriched with specific nucleosides, nucleotides, or mixtures thereof.
Infant formulas are derived, to a large extent, from cow's milk. After being diluted, the cow's milk is enriched with whey proteins, diverse carbohydrates, such as lactose, dextrinmaltose and starches, different mixtures of vegetal and animal fats, vitamins and minerals. These components are present in suitable amounts to meet the requirements of low birth weight newborns or those of at term healthy infants during the first and second semester of life.
Sometimes, infant formulas contain isolated milk proteins, isolated vegetable proteins or protein hydrolyzates, from different origins such as casein, lactalbumin, soy and meat. Also, these infant formulas have one or more carbohydrates (sucrose, dextrinmaltose and starch), mixtures of diverse kind of fats, minerals and vitamins, to meet not only the healthy newborns' nutritional requirements, but also of infants and children with clinical symptoms of lactose intolerance, protein intolerance and, in general, with diverse malabsorption-malnutrition syndromes.
The European Society of Pediatric Gastroenterology and Nutrition (ESPGAN), the American Academy of Pediatric (AAP), the Codex Alimentarius Mundi, and the European Community Council, among other organizations, have given general rules for the composition of infant formulas (ESPGAN Committee on Nutrition, Acta Paed Scand, Supl 262. 1977: ESPGAN Committee on Nutrition, Acta Paed Scand, Supl 287, 1981: ESPGAN Committee on Nutrition. Acta Paed Scand, Supl 302, 1982; ESPGAN Committee on Nutrition. Acta Paed Scand. Supl 330, 1987; AAP Committee on Nutrition, Pediatric Nutrition Handbook, 1979; AAP Committee on Nutrition, Pediatrics, 75, 976, 1985: EEC Council. 85/C 28/05 COM (84) 703 final, 1985; EEC Council, 86/C 124/06 COM/86 91 final, 1986 Codex Alimentarius Mundi, Codex Stan 72-1981).
As used herein, the term "infant formulas" is intended to refer to the well established understanding as defined by ESPGAN Committee on Nutrition, Acta Paed Scand, supl 262, pg 3, supra. and also the American Academy of Pediatrics (Pediatrics, Vol 57 no 2, pg 281, February 1976).
In general, infant formulas tend to have a composition qualitatively and quantitatively as similar as possible to human milk. Nevertheless, despite the efforts made by several researchers, infant formulas still have a number of differences in their composition compared to human milk. This is because the latter has many substances, such as immunoglobulins, free amino acids, polyamines, nucleotides, polyunsaturated fatty acids, etc, which are not present in cow's milk. Thus, it would be desirable that infant milk formulas have most of the substances present in human milk so as to produce the same physiological effects as human milk.
Nutritional products, such as those currently used in hospitals, special or for dietary purposes, are based on the utilization of diverse protein sources (casein, sodium and calcium caseinate, isolated soy protein, protein hydrolyzates and/or crystalline amino acids) mixtures of vegetable and animal fats, carbohydrates (basically glucose polymers), vitamins and minerals to meet, at least, the dietary intakes recommended for healthy individuals (Committee on Dietary Allowances, Food and Nutrition Board, Nat Acad Sci, 9th Ed. 1980).
Protein energy malnutrition (PEM) is found in many patients admitted to hospitals. This happens not only in developing countries, but also in those with a high socioeconomic level where the percentages of medical-surgical patients vary between 40-50 % (Bistrian et al. JAMA, 235, 1567,1976; G. Hill et al. Lancet, 1, 689, 1977; Gassull et al. Human Nutr: Clin Nutr, 38C, 419, 1984). Proper nutritional support for such patients, while not a primary mode of treatment is, nevertheless, an important factor for therapy and recovery. It is, therefore important to administer a nutritionally balanced diet given orally, enterally or parenterally, adequate to the needs of the patient. This is especially true for those patients where conventional feeding is contraindicated (gastroenterological patients) or is insufficient (hypercatabolic patients). The enteral or oral mode of administration of foods is preferable to parenteral modes (E. Cabre and M. A. Gassull, J. Clin Gastroenterol Nutr. 1, 97, 1986) because of the lower morbidity, trophic effect upon the intestinal mucose, lower necessity for instruments and lower costs.
Nutritional products for proper diets associated with parenteral administration should be formulated to meet the requirements of the individual needs in specific situations. Thus, complete balanced diets with an energy content between 130-150 Kcal/g nitrogen, are recomended for the preventive and repletive therapy in cases of PEM due to nervous anorexy, esophageal stenosis, maxillofacial surgery, chronic vasculo-cerebral disease, long evolution neurological syndromes, vascular surgery postoperative period, malabsorption syndromes, preoperative period, complete intestinal oclusion, preparation of colon (surgery, radiology and endoscopy) and, in general, in all cases when it is necessary to take a balanced diet of nutrients. Diets with a high content of nitrogen (80-120 Kcal/g nitrogen) are recommended for the nutritional therapy of burn patients or patients suffering cranial trauma, multiple trauma, open fractures, Crohn disease, ulcerous colitis, digestive fistula, sepsis, oncology surgery. oncological radiotherapy and chemotherapy, pre-and postoperative periods, orthopedic surgery, and, in general, for catabolic patients.
Diets containing protein hydrolyzates as a source of amino nitrogen are specially made for the nutritional support of patients with diverse malabsorption-malnutrition syndromes, such as short bowel, acute celiac disease, Crohn disease, chronic pancreatic insufficiency, cystic fibrosis, intestinal fistulas, postoperative nutrition, and the like.
Futhermore, such products can be made as specific clinical diets for specific diseases, such as hepatopathies, chronic renal disease, and chronic obstructive pulmonary disease.
In addition, there is a variety of dietary products marketed to meet the nutritional needs of various individuals. For example, many individuals desirous of achieving variyng degrees of weight loss, may benefit from the use of a special nutrition diet formulations to provide specific nutrients otherwise provided by a normal diet. Likewise, many people find it necessary to supplement their daily diet with additional nutrients due to age, allergy or physical afflictions.
As used herein, the term "nutritionally balanced diet formulations" is intended to refer to the above type of products.
Currently marketed nutrition products do not contain nucleic acids or their simpler compounds, either nucleosides and/or nucleotides, which are normally present in foods and carry out fundamental physiological functions, described further on.
In relation to the nutritional importance of nucleotides, some relevant aspects of these compounds such as their content in human milk, physiological effects in newborns, intestinal absorption, tissue utilization and effects upon cell immunity are shown below.
U.S. Pat. No. 4,544,559 teaches that human milk has a specific nucleotide content, very different from cow's milk. Human milk contains, at least, twelve different nucleotides, predominating cytidine monophosphate (CMP), adenosine monophosphate (AMP), uridine monophosphate (UMP), guanosine monophosphate (GMP), inosine monophosphate (IMP) and uridine derivatives, whereas cow's milk has very low amounts of CMP and AMP; it lacks the other nucleotides and has high amounts of orotic acid, which is absent in human milk.
Also, U.S. Pat. No. 4,544,559 teaches that a humanized milk enriched with nucleotides AMP, CMP, GMP, UMP and IMP in the same range as human milk, stimulates the development of Bifidobacterium bifidum Ti at the intestinal level. This bacterium comprises 80% of the total bifidobacteria present in the feces of breast-fed newborns. Furthermore, this humanized milk promotes serum fatty acid profile very similar to that found in newborns fed with human milk.
Ziro et al. U.S. Pat. No. 3,231,385 describes infant milk formulas supplemented with certain nucleotides to simulate human milk, improve the milk taste and lower the curd tension.
Nucleotides can be synthesized in most tissues by two processes: (a) de novo synthesis from the precursors which include pirophosphoribosilphosphate, glutamine, aspartate, glycine, formiate and carbon dioxide and (b) utilization of bases and the nucleosides liberated through the catabolism of nucleotides and nucleic acids contained in foods by the "salvage pathway" (S. Leleiko et al. J Pediatr Gastroenterol Nutr, 2, 313, 1983). This last way is an important alternative in the synthesis of nucleotides when the biosynthetic de novo pathway is hindered by an insufficient supply of precursors. Tissues such as bone marrow, intestine and the liver are heavily dependent on the salvage pathway. The activity of the "salvage pathway" has also been shown demonstrated in kidney, brain L and retina (P. Mandel, Traite de biochemie generale, Polonovski, Boulanger, Lemoigne. Wurmser, eds, Masson et Cie, Paris. 1972).
The intestinal mucose needs a continous supply of nucleotides or their precursors from dietary origin, apart from the hepatic supply by the vascular system, in order to maintain continuous synthesis of RNA.
It has been confirmed in cuts made in the small intestine of rats that the exogenous adenosine triphosphate (ATP) increases the intracellular concentration of this nucleotide and it has been observed that at temperatures over 20.degree. C. the marked exogenous ATP is absorbed by everted sacs of rat small intestine (J. Bronk and H. Leese. J. Physiol., 235, 183, 1973; J. Blair, M. Lucas and A. Matty, J. Physiol., 245. 333. 1975). Also, it has been shown in rabbit's ileum "in vitro" that, at low concentrations, the ATP as well as the nucleoside adenosine are absorbed through a carrier associated to the enterocyte membrane.
Since the carrier system works for ATP and adenosine, it is likely that the system also works for other purine nucleotides, because competitive inhibition measures have proved that any compound with a purine ring united to a ribose molecule is absorbed. (V. Harms and C. Stirling. Am. J. Physiol.. 233, E-47, 1977).
It has also been shown that the purines and pyrimidines in the RNA and DNA. present in the diet, are absorbed by mice, preferably as nucleosides. Between 2-5% of the nucleosides are used for nucleic acid synthesis in intestinal tissue, and citosine nucleosides are used for DNA synthesis, specially in the spleen (F. Sonoda, M. Tatibana, Biochem. Biophys. Acta, 521, 55, 1978).
It has also been shown that purine bases, such as adenine, guanine, hypoxanthine and xanthine are almost completely absorbed by rats. 4.5-6.5% being incorporated in tissues and in a greater proportion by the liver and intestine.
The absence of pyrimidine or purine derivatives in the diet is known to supress the normal function of T lymphocytes (F. Rudolph et al. Adv. Exp. Med. Biol, 165, 175. 1984), and to increase the mortality in experimental animals by staphylocoocus sepsis. The addition of pyrimidine and purine derivatives to the diet decreases the suceptibility of animals to infection (A. Kulkarni et al. JPEN, 10, 169, 1986). Thus, the effect of purines and pyrimidines on the immune function can be of great importance in a number of clinic situations, such as transplants of organs in patients, malnutrition recovery, in diverse chemotherapeutic regimens and in the treatment of leukemias derived from T cells. Accordingly, one of the objects of the present invention is to provide improved nutritionally balanced diet formulations.
Another object of the present invention is to provide non-milk infant formulas which more closely resemble the human milk of nursing mothers and also exhibit enhanced properties.
Still yet a further object of the present invention is to provide improved milk based infant formulas which not only closely resemble human milk, but which are more readily absorbed by the infant gut and enhance the infant's immune response.
These and other objects of the present invention will become more apparent from the discussion which follows.